Method of hardening contiguous areas



/ Jan. 11, 1944. DENNEEN Em 2,339,157

METHOD OF HARDENING CON'IIGUOUS AREAS Filed May 27, 1940 l I INVENTORPatented Jan. 11, 1944 2,339,157 METHOD or nanpnmc con'rrcuous AREASFrancis S. Denneen, Cleveland, and William C.

Dunn, Shaker Heights, Ohio, Ohio Crankshaft Company, Cleveland,

a corporation of Ohio Application May 27, 1940, Serial No. 337,428

4' Claims. ((11.219-13) The present application is a continuation inpart of our application Serial.No. 54,388 filed Dec. 14, 1935, nowPatent No. 2,202,759, issued May 28, 1940 and entitled fl-feat treatmentof shafts and the like" and is directed mainly to hardeningsubstantially all of the axially -ex-' tending surfaces of a shaft orsimilar, article in such a way that adjacent areas are hardened todifferent degrees and/or different depths, the apparatus employed beingadapted to hardenall of the surfaces substantially simultaneously and insuch manner that the hardened zones blend into each other without adistinctly marked line of change. However, the apparatus employed iscapable of beingso adjusted as to leave unhardened areas of any selectedwidths since in termediate unhardened areas are frequently required. I

In' view of the above conditions, the chief object of the presentinvention is to provide a method of hardening substantiallysimultaneously selected parts of a shaft or similar article,

adjacent parts blending together but being of different characteristics.Another object is to provide a method of hardening several areas of ashaft selectively to the same or different degrees of hardness andleaving intervening areas substantially unhardened. A further object isto provide a. method of controlling the rate and amount of quenching aswell as the rate and amount of heatingin such adjacent areas. Anadditional object is to provide a method which is suiiicientlyflexibleto permit the use of equipment which is readily applicable to othershafts of approximately the same diameter but having variously arrangedhardened zones.

With these and other objects in view, said invention then consists ofthe method hereinafter described. It will be understood that thefollowing description is not intended to limit the scope of thisinvention and that the invention may appear in many embodimentsdiffering in detail from this disclosure but within the scope of theappended claims.

The annexed drawing and following descrip tion set forth in detailcertain mechanism embodying the invention, such described means,however, constituting but one of the various forms inwhich the principleof our invention may be used.v

In said annexed drawing:

Fig. 1 illustrates the preferred form of our apparatus. Fig. 2 is asection on line 1-4 of Fig. l and diagrammatically includes means ofcontrol. v

assignors to The Ohio,

' In the apparatus illustrated in the above fisures, the shaft 12 isinserted in a series of parallel and relatively closely spaced inductorsl3, l4, l5, l8 and I1, thesurface of the shaft being spaced from theinner surfaces of the inductors. Heating current. is supplied by thehigh frequency generator 18 which delivers this current thru the powerlines is and 20. Suitable transformers having primaries Zl connectedacross these power lines and with secondaries 22 connected to theinductors serve as means for converting the relatively high voltagegenerator output into low voltage current of high'density at theinductors. Condensers such as 23 are connected across the primaries 'soas to tune the circuits for the most suitable heating con- -.ditions.The generator output is controlled by the field resistanc 24. Theconnections of the secondary coils. to Y the inductors are made atpoints such as 25 .and '28 which are substantially opposite for propercurrent distribution, the displaced position'sindicated in Fig. 1 beingfor ease of illustration. videa transformer for each inductor. However,under some conditions, when the equalization or distribution of currentto several inductors is not dimcult, two or more inductors are connectedto on secondary such asthe connections illustrated for inductors l4 and;

As it is frequently required to. regulate the heating and/or quenchingto control the depth of the hardened zone or its degree of hardness atvarious parts of the shaft, means is provided to automatically take careof such conditions. Forsuch parts as may require a deep hardened zone,as for instance the spline portion at 21, the heating is begun heresomewhat in advance of heating at other parts. This is accomplished byclosing switch 28 before closing otherof the pri-. mary. circuits andconsiderable heating is accomplished in advance after which theremaining circuits are closed.

The heating in various parts of shaft I2 is further controlled bychanging the direction of current in one or more of. the inductorsrelative to the direction of current in the other inductors. Thus if,for instance, the connections for the transformer supplying current toinductor 15 are reversed by means of switch 28a, the current in thisinductor atany instant willbe in a direction opposite to that which thiscurrent would have if the terminals had not been reversed, i. e., itwill be out of its original phase. The flux field produced by thisinductor will then oppose that of inductors H. and I! of which theconnec- It is customary to protions have not been chanced and in whichthe current thus remains in its tion.

materially out of phase relative to the current in inductor effected.

The automatic control of such heating and quenching is provided byrotating timer discs having contacts indicated at 3| and 32, the discsbeing driven by a synchronous motor M,

quenching fluid during and at terval of time he means or method statedby any of the following claims or the equivalent be employed. We,therefore, particularly point tlnctly claim as our, invention:

of such stated means or method out and disof inductors, the inductorsbeing spaced along said article, providing a supply varying current forthe inductors, each inductor producing a flux inductor being in timedrelation to the current supply to an adjacent inductor article betweenthe inductors, and interrupting the supply of inductors.

2. A method of surface hardening an article, the article being adaptedto be hardened by heatcancel the flux field in the space between theinductors to substantially eliminate a, aeneration or heating current inthe aforesaid intermediate part of the article, and timing the supply ofcurrent to one inductor relative to that being supplied to the other toprovide an interval in which substantial heating current is generated inthe intermediate part to produce a predetermined heating in said part,the heatin: in said part bein: substantially less than the heating inone of said zones.

FRANCIS s. DENNEEN. WILLIAM c. norm.

